. The structure and classification of birds . 248 STRUCTURE AND CLASSIFICATION OF BIRDS are in Bubo, where, as already explained, they are thinplates, hardly thicker than a piece of paper. So far Photo-dilus agrees with Strix ; but there are points in which theskull of this aberrant owl is nearer to the bubonine sectionof the order. It has not the occipital convexities which areso striking a feature of the skull of Strix. Finally Pliotodiliisis strigine in the non-extension over the occcipital region ofthe temporal fossse, which do so extend in many of theBubonidae. In Strix there is but one n
. The structure and classification of birds . 248 STRUCTURE AND CLASSIFICATION OF BIRDS are in Bubo, where, as already explained, they are thinplates, hardly thicker than a piece of paper. So far Photo-dilus agrees with Strix ; but there are points in which theskull of this aberrant owl is nearer to the bubonine sectionof the order. It has not the occipital convexities which areso striking a feature of the skull of Strix. Finally Pliotodiliisis strigine in the non-extension over the occcipital region ofthe temporal fossse, which do so extend in many of theBubonidae. In Strix there is but one notch on either side. FIG. 126.—SKULLS OF Strix (LEFT-HAND FIGUEE) AND Bubo (AFTER BEDIMED).E, prefrontal process ; W, maxillo-palatines. of the sternum ; in other owls, including Photodilus, thereare two. The vomer of the owls is not large,1 and behind itthere is a medio-palatine, at least occasionally present. The lacrymals, like the maxillo-palatines, with whichthey come into contact, are swollen and spongy. Thenostrils are often partly covered by ossified alinasals, andthere is a largely bony internasal septum. 1 Said by SHUFELDT to be absent in Speotyto. STR1GES iM. > In the foot of Strix (see fig. 127) the first phalanx of digitIII. is much less than the second in length ; in most otherowls (fig. 128) these two phalanges are small and subequal ;Plwtodilus is intermediate. The latter genus has the pecu-liarity that the last digit has only four phalanges insteadof five, the two basal ones being fused. The number of cervical vertebrae does not appear to vary.
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectbirds, bookyear1898
